Heat sealable fabrics



United States Patent 3,212,530 HEAT SEALABLE FABRICS Hans Meyer and Peter Meyer, both of 63 Jeddo Road, Shepherds Bush, London, England No Drawing. Filed June 9, 1961, Ser. No. 115,931 5 Claims. (Cl. 139420) The present invention relates to improvements in heat sealable fabrics such as are adapted for the price or identification marking of textile articles and is particularly concerned with fabrics strips or tapes from which temporary marking tabs or labels can be produced adapted to be attached under heat and pressure to textile articles, for example, articles to be subjected to laundry or drycleaning operations or articles to which price marking labels are attached, and which tabs or labels offer a required degree of adhesion, for example, such that they remain in position throughout laundry or dry-cleaning operations but can be removed at the completion of such operations without damage to the textile article.

Methods of marking articles to be laundered or drycleaned based on the use of heat sealable tabs or labels have been described in U.S. Patent Nos. 2,639,255, 2,639,266 and 2,828,776 and apparatus for attaching such tabs or labels to textile articles has been described in U.S. Patents Nos. 2,654,495, 2,654,496 and in co-pending patent application Serial No. 66,753 and also in British Patent No. 668,305.

As explained in such specifications the removal of the tab or label may be facilitated by the fact that part of the tab or label is not adhered to the article, and thus serves as a finger grip to assist removal.

Tabs or labels utilised for this purpose may be provided with an identification marking by a printing method. In many cases such tabs or labels are formed from a fabric in which some but not all of the yarns consist of a thermoplastic material such as a cellulose ester or polyvinylidene chloride. The marked tab or label is applied to the article to be marked under the action of heat and pressure and in some cases in the presence of a solvent for the thermoplastic material, particularly when cellulose acetate is used. In those cases in which a solvent is not applied, practical forms of such fabrics make use of a thermoplastic material having a softening point which lies above 100 C., but below the scorching temperature of textile materials, i.e., below 230 C. in most cases, but where a solvent is applied (it has the effect of temporarily softening the thermoplastic material) a thermoplastic material will normally be used which has a still higher softening temperature, but which can be softened by the application of the solvent.

U.S. Patent No. 2,828,776 is directed to a woven textile fabric different than claimed herein and which aimed without a particular formula to meet these special requirements and is based on particular weaves of a fabric consisting both of thermoplastic yarns and of non-thermoplastic yarns whereby a greater proportion of thermoplastic material is exposed on that face of the fabric which is applied to the article to be marked than on the other face.

It will be realised that, as explained in said last specification, for example, such tabs or labels have to fulfill various stringent requirements if they are to operate satisfactorily. The adhesion must be sufficient to enable the tab or label to remain in place on the article throughout the laundering or dry-cleaning operations involved, but, nevertheless, it must be possible to strip or peel off the tab or label at the end of such operations without damage to the article.

Other requirements for such tabs or labels are that they must be capable of accepting a visible identification mark- "ice ing by printing methods and such markings must remain legible right up to the completion of the laundry operations and up to the time when the tab or label is removed from the article. Such printing must, however, be confined to the tab or label and must not be transferred to the article so as to leave a permanent marking thereon. Further, after removal of the tab or label there must be substantially no residue of non-thermoplastic yarns or of thermoplastic material left on the surface of the article.

Again the tab or label must be permeable to the treatment liquids used in laundry or dry-cleaning operation so that proper cleaning effects are secured upon the part of the article lying under the tab.

Further, the fabric must itself have sufficient strength and coherence after heat and pressure has been applied, to withstand the pull which must be exerted when removing the tab or label from the article.

Quite apart from the requirements detailed above, it must obviously be possible to produce the tab or label at an economic price and, furthermore, the specific properties must be reliably and consistently obtainable, that is to say substantially every tab or label must have the required properties since any failure may have serious consequences in practical operating conditions. This is of primary importance as regards the adhesion property because if the tabs or labels were to become detached the customers identification is lost and the article itself is virtually lost, While if the adhesion were too great a considerable loss of time might result and the possibility of damage to marked articles would be increased.

It has been found that the performance of any particular tab or label is dependent on the structure of the fabric from which it is formed and on conditions external to the tab or label, such as the temperature, specific pressure and pressing time when applying the tab or label and the composition of any solvent which may be applied to the tab or label before it is applied to the article.

It is a matter of some difficulty to produce a tab or label fabric which fulfills satisfactorily and consistently the numerous requirements encountered in the marking methods referred to above, and the considerations pertaining for price marking are substantially the same.

Taking into account the various factors intrinsic to the tab or label and the various extrinsic factors relating to the manner in which the tab or label is applied to the article, it will be seen that a very large number of possibilities exist. As heretofore very little was known about the influence of the intrinsic factors, the tab or label fabric had to be chosen on a random basis or by trial and error. If the required performance was not then attained it was possible only to vary the extrinsic factors to secure optimum performance or even an acceptable performance, but the extrinsic conditions pertain to the users of the tab or labels and to the application of them to articles to be marked and it is obviously inconvenient and impractical to expect such users to modify the extrinsic conditions to secure consistent performance.

The main object of the present invention is to provide data and criteria whereby a tab or label fabric can be selected which satisfactorily and consistently fulfils the specialised requirements applicable to the temporary marking of textile articles and by which it becomes unnecessary to vary the extrinsic factors.

As far as the tab or label fabric is concerned the nature of the thermoplastic material used and the particular structure or Weave of the fabric must generally be chosen by reference to other considerations than the need to obtain a predetermined degree of adhesion, for example, price, body or firmness, dimensional stability, ability to accept markings, coherence, liability to fraying during washing or cleaning operations, or to leave traces of yarn or thermoplastic residue on the textile article after removal of the tab or label. All the properties specified represent predetermined or specified conditions of use of the tab or label fabric.

There are, however, a number of factors inherent in the design or weave of the fabric which can be varied and the present invention is based on the unexpected discovery that certain of these variable factors have a significant effect on the properties of a tab or label formed from such a fabric. By taking these factors into account it becomes possible to design a range of fabrics which fulfil the aforesaid predetermined or specified conditions, without the need to vary the extrinsic conditions.

It is well-known in woven fabrics that if a yarn is extracted from the fabric it is in most cases of an inherently corrugated or wavy form. This corrugation or waviness is often referred to as the crimp and is measured under ASTM Designation D39-49, No. 8, which reads as follows:

Two parallel lines 8 in. apart shall be marked on the fabric. Four of the yarns passing through these marks shall be revelled out to a distance of about 2 ins. beyond each mark, care being taken to avoid stretching the yarns. Each yarn shall be straightened by means of a machine which applies a load in grams of 131 divided by the number of thousands of yards of the yarn required to make 1 lb. The percentage crimp shall be calculated from the following formula:

Crimp (percent) (d- 8) where: d the average distance in inches between the marks on the yarns under the specified load.

Where fabrics are formed in part of thermoplastic warp yarns and in part of non-thermoplastic warp yarns the two types of yarn do not necessarily have the same degree of tension and crimp. Thus, for example, the thermoplastic yarns may be supplied at a lower tension and may in some cases be supplied by a positive let-01f motion. It has been discovered that in the case of fabrics for the production of marking tabs or labels of the character to which the present invention relates, and comprised in part by thermoplastic Warp yarns and in part by non-thermoplastic warp yarns, the crimp factor pertaining to the thermoplastic warp yarns is one of the important factors determining the properties of the fabric and its usefulness for use as a tab or label.

The variable factors which have a significant influence on the usefulness of a tab or label fabric may be summarized as follows:

(i) The crimp factor as defined above,

(ii) The denier of the thermoplastic warp yarns,

(iii) The count of the non-thermoplastic warp yarns,

(iv) The number of weft picks in unit length, and

(v) The number of thermoplastic warp yarns in unit length.

The terms denier as applied to thermoplastic yarns and count as applied to non-thermoplastic yarns have the meanings usual in the textile industry; the denier being the weight in gm. of 9000m of yarn, whereas the count is the number of hanks of 840 yds. of yarn to 1 lb. of yarn.

For a temporary marking label the degree of adhesion required may lie between upper and lower acceptance limits, i.e. an adhesion less than the figure above which there is a danger of damage to the articles when the tabs or labels are removed and greater than that below which there is danger of premature loss or inadvertent removal of the tab or label in the course of handling or treatment of the marked article. In many cases these limits are reispectively 280 and 900 gm. (as defined below) for a label about 1.3 cm. wide and about 2.5 cm. long (inclusive of the finger grip) but it is frequently desirable in many cases to choose a tab or label fabric in which the adhesion lies between 400 and 700 gm. while the preferred range lies between 500 and 600 gm.

The adhesion of the tab or label to the article is measured by fixing a piece of textile material bearing a tab or label about 1.3 cm. wide and about 2.5 long (inclusive of the finger grip) having a non-adhering finger grip portion at one end, to a suitable horizontal support and then applying a clip to the finger grip and exerting a pull exerted at a rate of about cm. per min. and directed along the face of the textile material, which tends to peel the tab or label away from the material from the finger grip edge to the opposite edge, the tab folding back on itself during the peeling operation. The tension applied to the tab is measured by a suitable gauge and provides the adhesion figure. Of course, determination of the adhesion in this way will be assessed on the basis of the average of a suitable number of tests.

A further object of the present invention is to provide design formulae pertaining to the component materials in the fabric structure and to the spacing of the various component yarns and to the relative length of the thermoplastic yarns incorporated in the fabric as compared with the length of the completed fabric whereby the design of a fabric to fulfill any specific requirements can be facilitated and in general design formulae can be evaluated for any particular fabric structure which is encountered in practice.

A still further object of the present invention is to provide specific design formulae applicable to the case where the thermoplastic yarns employed consist of cellulose acetate and in performance of this object the present invention further comprises a fabric selected in accordance with the design formula:

where m, n, o, q and r are numerical constants depending on the particular type of fabric structure, and C, P, D, N, E and A are variable terms defined as follows:

C is the count of the non-thermoplastic warp yarns and lies between 18s and 60s,

P is the number of weft yarns per cm. and lies between 8 and 34,

D is the denier of the cellulose acetate and lies between 280 and 600,

N is the number of cellulose acetate yarns per cm. and

lies between 2 and 24,

E is the crimp factor, which lies between 0 and 31%, and

A is the adhesion of the tab at the article to be laundered or cleaned expressed in gm. of pull necessary for re moval and lies between 280 and 900 gm.

If the fabric has a plain weave structure the numerical constants have the following values:

m=28.6, n=l.7, 0:335, q=16.9, and I=340.

If, however, the fabric is non-symmetric and includes a greater proportion of cellulose acetate yarn exposed on that face which is applied in contact with the textile article than on the exposed face, as disclosed (non-symmetric fabric but not following formula) in US Patent No. 2,828,776, the numerical constants may have the following values:

and in this case the crimp factor E lies between 0 and 9%.

The features of the present invention relate to various fabrics, and to various thermoplastic yarn materials. The following more detailed description and examples are however directed to fabrics in which the warp consists of cellulose acetate yarns alternating with non-thermoplastic yarns consisting of cotton or viscose, and the weft consists of cotton or viscose.

The fabrics given by way of example comprise two non-thermoplastic yarns arranged between adjacent cellulose acetate yarns, the sequence being one cellulose acetate yarn followed by two non-thermoplastic yarns, then one cellulose acetate yarn and so on. Each cellulose acetate yarn may comprise several component yarns to provide the required denier.

For general guidance it may be stated that, as related to the adhesion property, the following conditions hold: an increase of the crimp factor has the effect of increasing the adhesion, increasing the denier of the cellulose acetate yarns increases adhesion, reduction in the count of the non-thermoplastic warp yarns increases adhesion, increasing the number of thermoplastic warp yarns in unit length increases adhesion and decreasing the number of the weft picks in unit length increases adhesion.

The examples apply specifically to the attachment of a tab or label to an article intended to be subjected to laundry operations and to give a degree of adhesion which is such that the tab or label remains adherent to the article throughout laundry operations but can be peeled off at the end of said operations without damage to the article. It may be assumed for example that the size of the tab or label is approximately 1.3 cm. wide and approximately 2.5 cm. long and that the degree of adhesion required as measured by the pull exerted in the plane of the article along the longer dimension of the label is of the order of 280 to 900 gm. and preferably lies between 400 and 700 gm. or still more desirably lies between 500 and 600 gm.

Such tab or label is assumed to be pressed for a period of about 3 seconds on to the article by heated presser means operating at a temperature of about 140 C. and the pressure exerted by the presser members is about 2.1 to 2.8 kg. per square cm. After the label has been printed with an identification marking and before it is applied to the article, it is treated with a solvent consisting, for example, of an aqueous solution containing about 80% acetone (volume for volume).

Provision is made to ensure that the tab or label referred to has an edge portion about 0.6 cm. long which is not adhered to the article so that this portion can be gripped between the fingers when the tab or label is to be removed. The strip may be formed with an edge portion which is free of thermoplastic yarns; alternatively heat and pressure may be exerted in such manner that one edge portion is not subjected to the pressure.

The fabrics concerned are capable of receiving printed identification markings and of showing such markings in a clear legible fashion, and which otherwise satisfactorily fulfil the requirements of a tab or label for the temporary marking of textile articles.

The following examples comprise two separate groups. The first group consists of a plain weave fabric such as is described (plain weave but not following formula) in Example 2 of US. Patent No. 2,639,255 and for the design of such fabrics the following formula may be adopted.

where C, P, D, N, E and A have the meanings defined above.

Example 1 Suppose as a first example that a tab is required showing an adhesion of about 560 gms., and that a cellulose acetate of 300 denier is available, that 40s cotton is availbe obtained in several ways.

able and that a dense and compact fabric structure is required such as corresponds to a fabric having 25 picks per cm. Substituting these values in the above equation it will be seen that if the crimp factor B is chosen at the value 20 and N becomes 14 these requirements will be fulfilled. A crimp factor E of 20 corresponds to a measurement d in the ASTM Designation D39-49, No. 8, of 9.6 in.

Example 2 Suppose that cellulose acetate of 300 denier is no longer available but that 400 denier is available, calculation will show that if factor N is reduced to 9 a fabric will be produced having substantially the same adhesion property.

Example 3 Suppose now it is desired to reduce the cost of the fabric of Example 1 it will be appreciated that the simplest way would be to speed up the weaving procedure by reducing the number of picks per cm. Suppose that P were reduced to 20 it will be seen that a fabric having substantially the same adhesion properties could be obtained by utilising a cellulose acetate yarn of 400 denier, by employing a non-thermoplastic yarn of 30s count, and by making N 10 and E216. A crimp factor E of 16 corresponds to a measurement d in the ASTM Designation D39-49, No. 8, of 9.3 in.

Example 4 Suppose it were desired to increase the adhesion factor from a figure of about 560 gm. to 700 gm. without substantially increasing the cost of the tab fabric. This represents an increase of adhesion by and it will be seen from inspection of the formula that this result could For example the number of picks in Example 1 could be reduced to 20 which would give approximately the required increase and would additionally have the effect of reducing the cost of the fabric.

These examples and a number of other comparable examples are listed below where the several columns are headed with the letters C, D, P, N, A and E with the same meanings as above.

ASTM Example No. C D P N A E D3949 No. 8

405 300 25 14 562 20 9. 6 405 400 25 9 565 20 9. 6 305 400 20 10 598 16 9. 3 405 300 20 14 705 20 9. 6 405 280 25 14 528 20 9. 6 405 280 10 8 586 10 8. 8 205 450 34 18 574 20 9. 6 600 33 14 508 10 8. 8 605 540 30 5 591 15 9. 2 305 350 15 11 5B8 10 S. 3 50s 350 30 21 559 5 8. 4 503 400 28 11 538 15 9. 2 305 280 23 24 558 0 8. 0 205 540 25 8 535 15 9. 2 605 450 34 11 524 15 9. 2 185 400 20 5 579 30 10. 4

The following group of example relate to a fabric structure of the type disclosed in US. Patent No. 2,828,776 having a greater proportion of cellulose acetate exposed on the face which is to be attached to a textile article than on the opposite and exposed face. The formula pertaining to such a fabric is as follows:

wherein C, P, D, N and A have the same meanings as explained above and wherein the crimp factor E also has the same meanings but lies between the limits of 0 and 9%.

The following list of examples shows typical types of fabric selected in accordance with the above formula:

ASTM D39-49 NO. 8

Example No. C E

WWP WP V WWP' WWS mouscmooyswusmop wocotommocmocnwo mi cwscmawaqren It will be readily understood that formulae of a similar character but with different numerical constants can be established for different predetermined conditions, for example where a different type of thermoplastic yarn is employed, which may or may not require the use of a solvent or where a different weaving plan is employed.

Further small adjustments to the constant yarns in the above equations may be required when alterations in the extrinsic conditions, such as the specific pressure, temperature, nature of the solvent or tab area are involved.

The above particulars apply to fabric formed from unsized yarns; small variations may be expected in the case of fabrics wherein the yarns are sized before weaving and de-sized after weaving.

What we claim is:

1. A loomed fabric marking tab adapted to be attached by the action of heat and pressure to textile articles to be subjected to cleaning operations, said fabrics comprising 1) alternating thermoplastic and non-thermoplastic warp yarns and (2) non-thermoplastic weft yarns, said fabric being produced according to the formula:

wherein:

D is the denier of the cellulose acetate and lies between 2-80 and 600,

C is the count of the non-thermoplastic warp yarns and lies between 18s and 60s,

P is the number of weft yarns per cm., and lies between 8 and 34, N is the number of cellulose acetate yarns per cm. and

lies between 2 and 24,

E is the crimp factor, which lies between 0% and 31%,

and

A is the adhesion of the tab to the article expressed as the pull in gm. necessary for removal and lies between 280 and 900 gm.

2. A loomed fabric marking tab adapted to be attached by the action of heat and pressure to textile articles to be subjected to cleaning operations, said fabric comprising (1) alternating thermoplastic and non-thermoplastic warp yarns and (2) non-thermoplastic weft yarns, said fabric having a greater proportion of thermoplastic yarn on one face than on the other and being produced according to the formula:

wherein:

D is the denier of the cellulose acetate and lies between 280 and 600,

C is the count of the non-thermoplastic warp yarns and lies between 18s and 60s,

P is the number of weft yarns per cm., and lies between 8 and 34,

N is the number of cellulose acetate yarns per cm.

and lies between 2 and 24,

E is the crimp factor which lies between 0% and 9%,

and

A is the adhesion of the tab to the article expressed as the pull in gm. necessary for removal and lies between 280 and 900 gm.

3. A strip of woven loomed fabric for the formation of marking tabs having a width corresponding to the length of each tab, said tabs being severed transversely of said strip to form said marking tabs, said tabs adapted to be attached by the action of heat and pressure to textile articles to be subjected to cleaning operations, said fabric comprising (1) alternating thermoplastic and non-thermoplastic warp yarns and (2) non-thermoplastic weft yarns, said fabric having a greater proportion of thermoplastic yarn on one face than on the other and being produced according to the formula:

wherein:

D is the denier of the cellulose acetate and lies between 280 and 600,

C is the count of the non-thermoplastic warp yarns and lies between 18s and 60s,

P is the number of weft yarns per cm., and lies be tween 8 and 34, N is the number of cellulose acetate yarns per cm.

and lies between 2 and 24,

E is the crimp factor, which lies between 0% and 9%,

and

A is the adhesion of the tab to the article expressed as the pull in gm. necessary for removal and lies between 280 and 900 gm.

4. A strip of Woven loomed fabric for the formation of marking tabs having a width corresponding to the length of each tab, said tabs being severed transversely of said strip to form said marking tabs, said tabs adapted to be attached by the action of heat and pressure to textile articles to be subjected to cleaning operations, said fabric comprising (1) alternating thermoplastic and nonthermoplastic warp yarns and (2) non-thermoplastic weft yarns, said fabric having a plain weave and being produced according to the formula:

wherein:

D is the denier of the cellulose acetate and lies between 280 and 600,

C is the count of the non-thermoplastic warp yarns and lies between 18s and 60s, P is the number of weft yarn-s per cm., and lies between 8 and 34,

N is the number of cellulose acetate yarns per cm.

and lies between 2 and 24,

E is the crimp factor, which lies between 0% and 31%, and i A is the adhesion of the tab to the article expressed as the pull in gm. necessary for removal and lies between 280 and 900 gm.

5. The strip of claim 4 wherein said fabric is formed with one edge portion free of thermoplastic yarns wherein said edge portion forms a finger grip that does not adhereto said article.

References Cited by the Examiner UNITED STATES PATENTS 2,639,255 5/53 Meyer 28-73 2,828,776 4/58 Meyer 28-78 XR 2,998,631 9/61 Meyer et al. 28-73 EARL M. BERGERT, Primary Examiner.

RUSSELL C. MADER, Examiner. 

1. A LOOMED FABRIC MARKING TAB ADAPTED TO BE ATTACHED BY THE ACTION OF HEAT AND PRESSURE TO TEXTILE ARTICLES TO BE SUBJECTED TO CLEANING OPERATIONS, SAID FABRICS COMPRISING (1) ALTERNATING THERMOPLASTIC AND NON-THERMOPLASTIC WARP YARNS AND (2) NON-THERMOPLASTIC WEFT YARNS, SAID FABRIC BEING PRODUCED ACCORDING TO THE FORMULA: 7.5C-28.6P+1.7D+33.5N+16.9E-A=340 